This application claims priority of foreign document JP-11-048041, filed Feb. 25, 1999.
The present invention relates to a treatment instrument for an endoscope (hereinafter referred to as xe2x80x9cendoscopic treatment instrumentxe2x80x9d), which is inserted into the body via a treatment instrument insertion channel in the endoscope to perform high-frequency excision of an affected part.
There is a generally known example of an endoscopic treatment instrument to be inserted into the body via a treatment instrument insertion channel in an endoscope, which comprises an insertion section formed of a long, flexible tube, etc., and an electrically conductive cutting wire exposed to a distal end portion of the insertion section. High-frequency current is supplied to the cutting wire to effect excision of an affected part of a patient. This type of endoscopic treatment instrument is disclosed in, e.g. Jpn. Pat. Appln. KOKAI Publication No. 5-176940 and Jpn. Pat. Appln. KOKAI Publication No. 4-307055.
The treatment instrument disclosed in Jpn. Pat. Appln. KOKAI Publication No. 5-176940 is provided with an outer sheath through which the body of the treatment instrument is movably inserted. By axially moving the outer sheath relative to the body of the treatment instrument, the length of the cutting wire exposed to the outside of the outer sheath is varied.
In the treatment instrument disclosed in Jpn. Pat. Appln. KOKAI Publication No. 4-307055, the surface of the electrically conductive cutting wire exposed to the distal end of the insertion section is coated with electrically conductive Teflon.
Where an EST (endoscopic sphincterotomy), for example, is performed using a cutting wire, the following operation is carried out. A distal end portion of the insertion section of the endoscope, which was pre-inserted in the body of a patient, is situated near a papilla. Then, an insertion section of the endoscopic treatment instrument is inserted in the body via the treatment instrument insertion channel in the endoscope. A distal end portion of the insertion section of the treatment instrument is projected out of the endoscope from a forceps opening formed at the distal end of the treatment instrument insertion channel. Under endoscopic observation, the distal end portion of the insertion section of the treatment instrument is inserted in the bile duct beyond the papilla. In this state, high-frequency current is supplied to the cutting wire, and the papillary sphincter is high-frequency heated and cut by the cutting wire.
In the case where the EST is performed by means of the treatment instrument disclosed in Jpn. Pat. Appln. KOKAI Publication No. 5-176940, if the endoscope body or a tissue near the papilla is in contact with the cutting wire, it is necessary to move the outer sheath so as to prevent such contact while observing an endoscopic image. In this case, however, the outer sheath needs to be moved while the distal end portion of the tube of the treatment instrument body is inserted in the bile duct beyond the papilla. It is thus possible that the tube of the treatment instrument body may be removed from the bile duct or the papilla during the operation of moving the outer sheath.
On the other hand, where the part near the papilla has a peculiar shape, for example, in the case of diverticulosisi the papilla is located deeper than the peripheral tissue. In such a case, it is difficult to move the endoscope body closer to the papilla. In such a case of disease, it may be advantageous to use a treatment instrument with a long knife length, thereby to make the direction of extension of the bile duct coincide with the axis of the tube of the treatment instrument body and the direction of the knife. With the treatment instrument according to Jpn. Pat. Appln. KOKAI Publication No. 5-176940, however, there is a concern that a tissue near the papilla, which is not a region-of-interest, may be damaged by a proximal-side portion of the cutting wire. Moreover, in this state, since the cutting wire is in contact with many body tissues, the density of electric current at the region-of-interest decreases and the excision of the papilla becomes difficult.
The treatment instrument according to Jpn. Pat. Appln. KOKAI Publication No. 5-176940 includes means for controlling the direction and shape of the distal end portion of the tube of the treatment instrument body by using an operating wire. It is very difficult, however, to perform at the same time the works for operating the outer sheath, the cutting wire, and the wire for changing the direction and shape of the distal end portion of the tube of the treatment instrument.
With the treatment instrument disclosed in Jpn. Pat. Appln. KOKAI Publication No. 4-307055, it is possible to prevent the cutting wire from adhering to the tissue in contact, but it is difficult to prevent the cutting wire from coming in contact with a body tissue which is not a region-of-interest.
The present invention has been made in consideration of the above circumstances, and its object is to provide a treatment instrument for an endoscope which is capable of enhancing the safety and operability of an EST (endoscopic sphincterotomy).
In order to achieve the object, there is provided a treatment instrument for an endoscope which comprises: a main body, a cutting wire and an insertion portion. The cutting wire has an insertion portion inserted in the main body and an exposed portion situated at a distal side of the insertion portion and exposed out of the main body. The cutting wire is supplied with high-frequency current, and the insulating member electrically insulates a peripheral surface of the cutting wire. The insulates member insulating that part of the exposed portion, which is other than a non-insulated portion extending in a range of 5 mm to 15 mm from a distal end of the exposed portion. And the excision portion is formed of the non-insulated portion of the cutting wire.
In the present invention, only that portion of the exposed portion of the cutting wire, which is in the range of 5 mm to 15 mm from the front end of the exposed portion, can be provided with the function of an excisable knife. In the EST, only the thickness portion of the papilla can be cut. In this case, no high-frequency current is supplied to the insulated portion of the exposed portion of the cutting wire, from which the excision portion is excluded, even if the insulated portion is put in contact with the body tissue. Thus, damage to other tissues around the papilla and to the endoscope can be prevented as much as possible. In addition, the length of the excision portion having the function of a knife is small, and the region of the living tissue, to which high-frequency current is applied, is small. Accordingly, the density in current increases and the excision can be exactly performed.
Therefore, according to the present invention, the safety and operability of the EST (endoscopic sphincterotomy) is enhanced.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.